The eXtensible Messaging and Presence Protocol aka as Jabber (the protocol was originally named Jabber and was developed by the Jabber open-source community) is a protocol to exchange messages between 2 entities. Those messages are transmitted over the wire in the XML format. It's used by Jabber, Google Talk, Google Wave, Pidgin, Kopete, and all sorts of open source instant messaging applications.

Ruby's standard library is a treasure trove of useful classes, and the Pathname class is certainly one of them. Introduced in Ruby 1.9, Pathname represents a path on the file system, providing convenient access to functionality that is otherwise scattered across a handful of other classes like File, FileTest, and Dir.